This invention relates to an apparatus for automatically starting and stopping an engine by automatically stopping the engine when a vehicle stops at an intersection to wait a signal so as to save the fuel consumption of the engine.
A conventional apparatus of this type is disclosed in Japanese Utility Model Publication No. 19,317/1978 official gazette, and its circuit arrangement is shown in FIG. 1. In the figure, numeral 1 designates a battery carried on a vehicle as a power source. Numeral 2 designates a key switch which connects a battery terminal 2B to an ignition terminal 2A or a starter terminal 2C to supply a power source voltage. Numeral 3 designates an ignition circuit of an engine having ignition coils 3L. Numeral 4 designates a normally open start switch. Numerals 5 and 6 designate the coil and the self-holding contacts of a self-holding relay, and when the coil 5 is energized, the closure between terminals 6a and 6b is switched to the closure between terminals 6a and 6c, a voltage of the ignition terminal 2A is applied through the terminals 6a and 6c and a normally closed cancel switch 7 to the coil 5, and the contact 6 is self-held by the coil 5. Numeral 8 denotes a starter for starting the engine. Numeral 9 denotes an ignition energization control circuit, which is energized by the self-holding of the contact 6 to control the energization of the ignition circuit 3 through a relay 9L. Numeral 10 indicates a starter energization control circuit, which controls the energization of the starter 8 through a relay 10L when the contact 6 is self-held. Numeral 11 indicates a lighting switch closed in response to the lighting of a headlight for applying a positive voltage applied to a terminal 11a to the ignition energization control circuit 9, numeral 12 indicates a reverse switch closed when a vehicle moves backwards for transmitting a positive voltage applied to a terminal 12a to the ignition energization control circuit 9, and numeral 13 indicates a normally closed water temperature sensor which opens when the water temperature of an engine coolant becomes a high temperature to overheat to interrupt the grounded state. Numeral 14 designates a turn signal switch which closes when the vehicles turns to the right to transmit a positive voltage applied to a terminal 14a to the ignition energization control circuit 9, numeral 15 designates a vehicle speed sensor which intermittently generates a travel signal by a rotating permanent magnet (not shown) fixed to an axle when the vehicle travels, and numeral 16 designates an accelerator switch which closes when an accelerator pedal is depressed to become a grounded state. Numeral 17 indicates a first clutch switch which opens when a clutch is completely engaged and closes when the clutch pedal is depressed to collapse the completely engaged state to become a grounded state, thereby generating a depression detection signal of a first detection signal, numeral 18 indicates a slope switch which detects a slope when the vehicle arrives at the slope to close and becomes a grounded state, and numeral 19 indicates a second clutch switch which closes when the clutch pedal is fully depressed so that the clutch is completely isolated to become a grounded state, and generates an isolation detection signal of a second detection signal. Numeral 20 denotes an engine start detecting circuit which detects the voltage generated from an alternator 20a produced by the rotation of the engine to indirectly detect the start of the engine, and interrupts the starter energization control circuit 10 to interrupt the energization of the starter 8. Numerals 9D.sub.1 -9D.sub.6 designate diodes, numerals 9R.sub.1 -9R.sub.6 designate resistors, numerals 9C.sub.1, 9C.sub.2 designate capacitors, numerals 9Tr.sub. 1 -9T.sub.r4 designates transistors, numerals 10Tr.sub.1, 10Tr.sub.2 designate transistors, and numerals 20Tr.sub.1, 20T.sub.2 designate transistors.
The prior-art apparatus operates as described below. In order to initially operate the device, the key switch 2 is closed to close the start switch 4. Thus, the coil 5 is energized through the key switch 2 and the start switch 4 from the battery 1, the terminals 6a and 6c of the contact 6 are closed and self-held, and the circuits 9, 10, 20 are energized. When the engine is started at this time so that the vehicle travels, the vehicle speed sensor 15 operates to become ON and OFF, a positive voltage is charged at the condensor 9C.sub.2, the transistor 9Tr.sub.2 is thus conducted, while the transistor 9Tr.sub.3 is interrupted, and the output transistor 9Tr.sub.4 is conducted. Thus, the ignition energization relay 9L is energized to close its contacts, thereby supplying a current to the ignition circuit 3 from the battery and allowing the engine to continuously operate.
The operation of the apparatus when the vehicle thereafter stops will be described. When the vehicle now stops, the vehicle speed sensor 15 stops generating the travel signal. The clutch pedal 22 is disposed at the position 22b in FIG. 2 in the state that the clutch pedal is not yet released at this time, the clutch switches 17 and 19 are closed to allow the transistor 9Tr.sub.1 to be interrupted. Thus, the capacitor 9C.sub.2 is charged, the transistor 9Tr.sub.4 is thus conducted to energize the relay 9L to close its contacts, thereby energizing the ignition circuit 3 from the battery, and the engine is not stopped. When a foot 21 is thereafter isolated from the clutch pedal 22 while the vehicle remains stopping and the clutch pedal 22 is moved to the position designated by a solid line in FIG. 2, the clutch switches 17 and 19 are opened, and when the accelerator switch 16 and the slope switch 18 are opened, the transistor 9Tr.sub.1 is conducted. When the turn signal switch 14 is further opened, the condenser 9C.sub.2 becomes zero volt, and the transistor 9Tr.sub.3 is conducted. When the lighting switch 11 and the reverse switch 12 are opened in this state and the water temperature sensor 13 is closed, the transistor 9Tr.sub.4 is interrupted, the relay 9L is deenergized to open its contacts, thereby interrupting the energization of the ignition circuit 3 from the battery and stopping the engine.
The engine should not be automatically stopped when the slope switch 18 is closed, the turn signal switch 14 is closed, the reverse switch 12 is closed, the lighting switch 11 is closed and the water temperature sensor 13 is opened. In all cases, the transistor 9Tr.sub.4 is conducted, and the engine is not stopped.
The automatically starting operation of the engine will be then described. When the vehicle is now stopped so that the engine is stopped, the alternator 20a does not generate, the transistor 20Tr.sub.1 is interrupted while the transistor 20Tr.sub.2 is conducted. Since the second clutch pedal 19 is released when the clutch pedal 12 is not depressed by the foot 21, a base current is supplied through a resistor 10R and a diode 10D to the transistor 10Tr.sub.1, and the transistor 10Tr.sub.1 is conducted, while the transistor 10Tr.sub.2 is interrupted, thereby deenergizing the relay 10L to open its contacts and thus interrupting the energization of the starter 8. When the clutch pedal 22 is depressed in this state, the pedal 22 is first moved to the position designated by broken line 22a to close the first clutch switch 17, thereby energizing the relay 9L to close its contacts and supplying a current to the ignition circuit 3 from the battery. When the clutch pedal 22 is then fully depressed so as to completely isolate the clutch, the second clutch switch 19 is closed to ground the base of the transistor 10Tr.sub.1 through a diode 10D and to allow the transistor 10Tr.sub.1 to be interrupted and the transistor 10Tr.sub.2 to be conducted. Thus, the relay 10L is energized to close its contacts to energize the starter 8, and the engine is automatically started. In this manner, the alternator 20a generates to conduct the transistor 20Tr.sub.1 while to interrupt the transistor 20Tr.sub.2. Thus, the transistor 10Tr.sub.1 is conducted, while the transistor 10Tr.sub.2 is interrupted, thereby deenergizing the relay 10L to open its contacts. Thus, the starter 8 is stopped. In summary, the above-described operations of the apparatus are listed in Table 1 below.
TABLE 1 ______________________________________ Engine start Engine stop ______________________________________ First clutch ON to energize OFF switch 17 ignition circuit 3 Second clutch On to energize switch 19 starter 8 ______________________________________
However, in the prior-art apparatus described above, it has such disadvantages that, when the clutch pedal 22 is depressed, the starter 9 is started even without occupant's intension of starting, and when the depression of the clutch pedal 22 is released without shifting a transmission to neutral position, an engine stop occurs, resulting in economical loss.